So i had sex and i m on birth control but i was really late taking the pill a couple days before so i got plan b just to be sure. i have missed 2 peri?

Can do preg. test: Pregnancy is the most common cause of a missed period. If not pregnant, other causes of a late or missed period include: excessive weight loss or weight gain, increased exercising, emotional stress, having an illness, traveling, medicines (such as birth control pills, Plan B), hormonal disorders, etc… A home pregnancy test is very accurate 3 weeks after sex or 1 week after missing a period.

You have missed: 2 periods since taking Plan B? If yes - taking a pregnancy test is very important. Whether the test is + or - , it is important to advise your gynecologist because your cycle is now irregular.